Cis-2-methyl-oct-5-en-2-yl acetate

ABSTRACT

2-Alkyl-oct-5-en-2-ols and their esters characterized by the structural formula ##STR1## wherein R represents alkyl having from 1 to 8 carbon atoms and R 1  represents hydroxyl or R 2  COO--, wherein R 2  represents alkyl having from 1 to 8 carbon atoms, aryl or aralkyl. These compounds can be in the cis or trans forms or mixtures thereof. The compounds have very pleasant, strong and long lasting green, floral, rosy aromas and are useful as fragrances or as components in fragrance compositions.

This is a division of application Ser. No. 432,012, filed Jan. 9, 1974,now U.S. Pat. No. 3,966,648, which was a division of Appln. Ser. No.211,789 filed Dec. 23, 1971, now U.S. Pat. No. 3,859,366.

This invention relates to the art of fragrance compositions and, moreparticularly, to a novel class of compounds possessing a characteristicaroma. More specifically, this invention is directed to a novel class ofuseful compounds, their preparation and the utility of these compoundsas fragrances or as components in fragrance compositions.

The art of perfumery began, perhaps, in the ancient cave dwellings ofprehistoric man. From its inception, and until comparatively recently,the perfumer has utilized natural perfume chemicals of animal andvegetable origin. Thus, natural perfume chemicals such as the essentialoils, for example, oil of rose and oil of cloves, and animal secretionssuch as musk, have been manipulated by the perfumer to achieve a varietyof fragrances. In more recent years, however, research perfume chemistshave developed a large number of synthetic odoriferous chemicalspossessing aroma characteristics particularly desired in the art. Thesesynthetic aroma chemicals have added a new dimension to the ancient artof the perfumer, since the compounds prepared are usually of a stablechemical nature, are inexpensive as compared with the natural perfumechemicals and lend themselves more easily to manipulation than naturalperfume chemicals since such natural perfume chemicals are usually acomplex mixture of substances which defy chemical analysis. In contrastthereto, the synthetic aroma chemicals possess a known chemicalstructure and may therefore be manipulated by the perfumer to suitspecific needs. Accordingly, there is a great need in the art offragrance compositions for new compounds possessing specificcharacteristic aromas.

The principal object of the present invention is to provide a new classof aroma chemicals consisting of 2-alkyl-oct-5-en-2-ols and theiresters.

Another object of the present invention is to provide a specific classof compounds having a characteristic aroma which is utilized in thepreparation of fragrances and fragrance compositions.

These and other objects, aspects and advantages of this invention willbecome apparent from a consideration of the accompanying specificationand claims.

In accordance with the above objects, there is provided by the presentinvention a novel class of compounds characterized by the structuralformula ##STR2## wherein R represents alkyl having from 1 to 8 carbonatoms and R¹ represents hydroxyl or R² C00--, wherein R² representsalkyl having from 1 to 8 carbon atoms, aryl or aralkyl.

These compounds have very pleasant, strong and long lasting green,floral, rosy aromas and are useful as fragrances or as components infragrance compositions.

Representative alkyl groups characterized by R and R² in the aboveformula include methyl, ethyl, n-propyl, i-propyl, n-butyl, i-butyl,tert-butyl, n-amyl, i-amyl, tert-amyl, n-octyl.

Groups other than alkyl characterized by R² in the above formula includephenyl, naphthyl and phenylalkyl and the like.

It should be understood that the scope of the present inventionencompasses both the cis and trans forms, as well as mixtures thereof,of the novel compounds of this invention. The precursor compounds can bethe cis, trans or mixtures of both as desired to provide the compoundsof this invention.

The novel alcohols of this invention are prepared by reacting a methylketone characterized by the structural formula ##STR3## wherein R hasthe same meaning as defined hereinbefore, with 3-hexenyl magnesiumhalides as illustrated in the following equation (wherein X represents ahalogen; chlorine, bromine or iodine): ##STR4##

Alternatively, the novel alcohols of this invention can be prepared byreacting 3-hexenyl methyl ketone with alkyl magnesium halides of theformula RMgX, wherein R and X have the same meaning as definedhereinbefore. Such a reaction can be illustrated by the followingequation: ##STR5##

The novel esters of this invention can be prepared by reacting the2-alkyl-oct-5-en-2-ols with an appropriate organic acid as illustratedin the following equation: ##STR6## wherein R and R² have the samemeaning as defined hereinabove.

The reaction conditions are not critical but should be such as tofacilitate the preparation of the products. Thus, the Grignard reactionis normally conducted at a temperature of from ambient temperatures upto about 150° C. and the esterification reaction is normally conductedwithin this same range.

The novel compounds of this invention are useful as fragrances in thepreparation and formulation of fragrance compositions such as perfumesand perfumed products due to their pleasing, strong and long lastingaroma. Perfume compositions and the use thereof in cosmetic, detergentand bar soap formulations and the like are exemplary of the utilitythereof. Likewise, these novel compounds can be utilized as the primaryfragrance in many such compositions.

The compounds of this invention are used in concentrations of from traceamounts up to about 50 percent of the fragrance composition into whichthey are incorporated. As will be expected, the concentration of thecompound will vary depending on the particular fragrance desired in thecomposition and even within the same composition when compounded bydifferent perfumers.

The following examples will serve to illustrate certain specificembodiments within the scope of this invention and are not to beconstrued as limiting the scope thereof.

EXAMPLE 1 cis-2-methyl-oct-5-en-2-ol

12.2 grams of magnesium were mixed with 50 ml. of anhydroustetrahydrofuran and activated with 0.5 ml. of methyl iodide. To thismass a solution of 59.3 grams (0.5 moles) of cis-1-chloro-3-hexene in150 ml. of tetrahydrofuran was added drop-wise with stirring. A greenishturbid solution formed and an exothermic reaction was started by warmingthe mixture to 55° C. and adding a few drops of methyl iodide. A fastexothermic reaction started which was controlled with a cold water bathto keep the temperature at about 50° C. A clear brown solution formed.This solution was chilled in an ice bath and 39.1 grams (0.55 moles) ofacetone, diluted with the same volume of tetrahydrofuran, was added atsuch a rate that the temperature remained at about 20° to 25° C.Stirring at room temperature was continued for 15 hours and the complexwas decomposed with ice-concentrated ammonium chloride solution. 68.1Grams of a crude product with an n_(D) ²⁵ = 1.4435 was obtained. Afterfractional distillation 48.2 grams of a product which had a boilingpoint of 88° to 89° C. at 20 mm. of Hg. was obtained which had an n_(D)²⁵ = 1.4425 and was found to be cis-2-methyl-oct-5-en-2-ol. The materialwas submitted to a fragrance panel for aroma characterization and it wasdescribed as having green, grass, sweet, floral and lavender aromas.

EXAMPLE 2 cis-2-methyl-oct-5-en-2-yl acetate

A mixture of 17.8 grams (0.125 moles) of cis-2-methyl-oct-5-en-2-ol, 20ml. of pyrridine and 15 grams of acetic anhydride was maintained atambient temperatures for 15 hours after which time period it wasrefluxed for 5 hours. Distillation gave 21.7 grams of a crude productwith an n_(D) ²⁵ = 1.4315. The crude material was distilled resulting in18.1 grams of product which had a boiling point of 90° to 91° C. at 20ml. of Hg. and which had an n_(D) ²⁵ = 1.4325 which was found to becis-2-methyl-oct-5-en-2-yl acetate. The material was submitted to afragrance panel for aroma characterization and it was described ashaving green, leafy, earthy, ozone and greenhouse aromas.

While the invention has been described herein with regard to certainspecific embodiments, it is not so limited. It is to be understood thatvariations and modifications thereof may be made by those skilled in theart without departing from the spirit and scope of the invention.

The embodiments of this invention in which an exclusive property orprivilege is claimed are defined as follows: 1.Cis-2-methyl-oct-5-en-2-yl acetate.